Technology computer aided design (TCAD) is a branch of electronic design automation that models semiconductor fabrication (typically referred to as “process TCAD”) and semiconductor device operation (typically referred to as “device TAD”). These techniques respectively include the modelling of process steps (e.g., diffusion and ion implantation) and the modelling of electrical device behaviors based on fundamental physics (e.g., the doping profiles of the devices). TCAD may also include the creation of compact models (e.g., SPICE transistor models), which try to capture the electrical behavior of such devices but do not generally derive them from the underlying physics.
The physics and modeling of devices in integrated circuits is dominated by metal-oxide-semiconductor (MOS) and bipolar transistor modeling. However, other devices, such as memory devices, are also important and have different modeling requirements. Physics-driven device modeling is intended to be accurate, but it takes a long time to get the full hardware data for the TCAD models, and is thus not typically fast enough for higher level tools, including circuit simulators such as SPICE. Therefore circuit simulators normally use the more empirical compact models that do not directly model the underlying physics. However, compact models are not accurately modeled from first principles, and so resort is taken to fitting experimental data.